1. Field of the Invention
The present invention relates to rotary lobe pumps and, more particularly, to a keyed wear plate for the curved chamber walls of such rotary lobe pumps.
2. Description of the Prior Art
Rotary lobe pumps are well known industrial pumps which have been in common use for about forty years. A pair of counter rotating interlocking lobe rotors in a pump chamber draw fluid from an input port and expel the fluid through an output port. The pump is well suited to low velocity, high density fluid, especially sludge-like fluids. Examples of typical applications of rotary lobe pumps are chemical slurries, milk and sewage.
Such rotary lobe pumps typically include a pump chamber which houses the two lobe rotors and which defines an obround side wall with a removable front cover plate being provided at a front end of the pump chamber for selectively allowing access thereto. One lobe rotor is mounted on a drive shaft and the other on a driven shaft with the latter being driven by the drive shaft via timing gears. The pumping action of the pump results from the lobes which are interlocked and which turn at a same angular speed while maintaining the same relative phase angle. The rotors during the rotation thereof make peripheral sliding sealing contact with the walls defining the pump chamber, namely the obround side wall and the end walls which include the front cover plate and a rear wear plate.
With time, the lobe rotors wear out the obround side wall of the pump chamber thereby slowly reducing the efficiency of the seal which exists and which is necessary between the lobe rotors and the obround side wall. Furthermore, the end walls of the pump chamber, namely the front cover plate and the rear wear plate, also wear out in view of the sliding sealing contact thereof with the end surfaces of the lobe rotors, whereby these components have to be periodically replaced in order to ensure an appropriate seal. On the other hand, the peripheral obround side wall is not replaceable without replacing the pump housing of the rotary lobe pump.